Undersized Tomatoes - Knowledgebase Question

My tomatoes, especially early in the season, never seem to grow to the sizes advertised in the seed catalogs. What am I doing wrong? What nutrient in the soil is most responsible for fruit sizes in tomatoes and other nightshade crops?

If the plant is not growing or producing to its full potential, it may not be getting what it needs. To begin with, cultivate the soil deeply and add organic matter to help hold moisture, provide nutrients, and make it easy for the roots to explore. Locate your veggie garden in a site that will receive the most sunshine possible. Start your seeds indoors so your transplants will be ready to take off and grow as soon as the air and soil temperatures are warm. Be sure to give your plants an inch of water per week; water deeply so the entire root system can access the moisture. Fertilize when the fruits start to form. Use a 5-10-10- or a 10-20-20 formulation. (The first number is nitrogen - for green growth, the second number is potassium - for flower and fruit production, the third number is phosphorus - for root development.) This is rather simplistic; all of these minerals work together, but it's easier to remember the fertilizer formula this way! The only other consideration is to choose a variety of tomato that has time to mature in your summer conditions. If you have a short growing season, choose a tomato that will mature in 70 days or less. If your season is long, choose something like a beefsteak. Remember that when the weather is too hot, some plants stop growing and producing until the weather cools down a bit. If you provide all that the plant expects it will reward you with plump, juicy tomatoes.